LAST NOVEMBER, Attorney General Eric H. Holder Jr. announced that the federal government would prosecute Sept. 11, 2001, mastermind Khalid Sheik Mohammed in a Manhattan federal courthouse.

One year later - and nine years after the attack - Mr. Mohammed has yet to be brought to justice. The administration's paralysis is as confounding as it is damaging.

The Authorization for the Use of Military Force allows the administration to continue to hold Mr. Mohammed without trial. Preventive detention should be available to a president in cases in which there is not enough admissible evidence to bring a prosecution but where intelligence reports indicate that a suspect is too dangerous to release. The White House and Congress should work together to fashion a legal framework to govern such cases.

But the government has a moral and legal obligation, and strong policy reasons, to bring formal charges whenever possible. Detention without trial should not be a default position to avoid tough political calls.

The decision to press ahead in a New York City federal court was informed by the court's successful record in legally complicated and politically charged cases. But Mr. Holder failed to lay the political groundwork for his decision, and his plan crumbled when New York officials and a bipartisan group in Congress questioned the wisdom and enormous expense of holding a trial just blocks from Ground Zero.

A federal court trial is still a possibility. Charges may be brought in any of the three jurisdictions where the attacks occurred: the Southern District of New York; the Eastern District of Virginia, site of the Pentagon; and the Western District of Pennsylvania, where the fourth plane hijacked on Sept. 11 crashed into a Shanksville, Pa., field. If an urban center is believed to pose too much of a security challenge, the trial could be held on a military installation or in a courthouse in a less densely populated part of the jurisdiction.

Congress, however, has forbidden the use of federal funds to bring detainees into the United States for trial or detention. This is an egregious encroachment on executive prerogatives - and one that the administration should have more vigorously challenged.

Still, the administration could conceivably, with congressional buy-in, convene a federal court at Guantanamo that could serve as an extension of one of the three recognized jurisdictions. It also could explore whether Mr. Mohammed could be video-conferenced into a trial that would be held on U.S. soil, as long he was given ample opportunity to contribute to his defense.

Military commissions are another legitimate alternative. Revamped in 2009, they include many of the same legal protections inherent in federal court proceedings. Unlike federal courts, they have not been tested and will likely be subject to legal challenges that could cause lengthy delays. But it's hard to imagine a delay longer than that caused by the administration's abdication.